A typical electric motor includes a stator and a rotor. The stator is the stationary section of the electric motor, whereas the rotor is its rotating section. The rotor typically provides a rotational motion to a load connected to it.
In at least one known application of the electric motor, it is used as part of a vibrator assembly. In a vibrator assembly, the rotor of the electric motor has an unbalanced cantilevered mass connected to the rotor of the electric motor through a shaft. The vibrator assembly is often used in devices, to provide haptic feedback to the user with a vibratory force. Currently, many electronic devices, for example, many mobile phones and pagers, utilize the vibrator assembly to produce vibration for at least some forms of a call alert. The electric motor gets energized and the unbalanced mass attached to it starts rotating as soon as the motor detects a signal associated with an incoming call, which provides a vibratory motion to the electronic device. When being rotated, the mass is often extended away from the body of the motor along the length of the shaft in a cantilevered configuration in order to minimize any friction and/or interference between the motor and the mass.
However, in certain situations, when the electronic device is dropped accidentally, there is a risk of the shaft being bent due to the weight and the extended position of the cantilevered mass attached to it. In a still worse scenario, the shaft can be completely disconnected from the electric motor or the weight may get knocked off from the shaft, thereby damaging the electronic device and/or affecting the device's ability to produce future vibrational forces.
In an attempt to avoid the above noted bending or deformation, some designs have attempted to use a high-grade material with a higher tensile strength from which the shaft is manufactured. However, various tests conducted on shafts composed of different materials have shown that the shafts composed of lower tensile strength materials generally have a higher fracture resilience than the shafts composed of higher tensile strength materials under at least some conditions of impact. In other words, while some harder materials had a greater resistance to bending, they often showed a greater propensity to crack or break under the same circumstances. Furthermore, it has also been demonstrated that under at least some expected usage conditions that even many of the higher-grade materials including at least some higher tensile strength steels still may not be able to withstand the maximum anticipated stresses likely to be encountered when the device is dropped. Moreover, a higher-grade material can also increase the cost of the shaft and consequently the cost of the electric motor.
In light of the above-mentioned facts, there exists a need for a method and system for preventing and or reducing the possibility of the shaft of an electric motor from getting damaged or bent in the event an electronic device comprising the electric motor is dropped.